Moin' and thanks! I'm going to take a further look at the objects within the pool and report back my findings. Cheers, Kees On 05/02/2026 20:36, Eugen Block via ceph-users wrote:
I've been searching the list for my own report from last year maybe, when we finally got rid of our cache tier as well. I can't really find it though, so I'm gonna summarize again how we managed to get out of it.
After setting the cache mode to proxy and failing to flush/evict (also with "no such file or directory" messages), I gradually reduced the cache pool size from 260 GB in steps of 40 GB or so, not sure anymore .Suddenly Ceph was able to flush and evict again. I reduced the target_max_bytes to 1000000, only rbd_header objects remained in the pool, but those couldn't be flushed/evicted anymore:
failed to evict /rbd_header.133ba5e7513046: (16) Device or resource busy rbd_header.8fbda012200854
Unfortunately, we didn't find a promsing way to get rid of them while the images were in use. I had played around in a test cluster and ignored the header objects when remocing the cache tier, and it seemed to work (since the rbd_header objects should be identical in the backing pool as well), but it didn't feel safe and we were really uncomfortable trying it in production. So in the end, we shut down our VMs to be able to flush/evict everything and safely got rid of the cache tier.
I know this isn't really helpful, but maybe next time I find my comment on the list. 🙂